CN106597421B - Time delay and time delay rate method for fast searching in the antenna array of strange land based on prediction model - Google Patents
Time delay and time delay rate method for fast searching in the antenna array of strange land based on prediction model Download PDFInfo
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The invention discloses the time delays and time delay rate method for fast searching in a kind of strange land antenna array based on prediction model, method includes the following steps: predictor calculation, prediction model fitting and residual error search.Time delay and time delay rate method for fast searching of the invention introduces the prediction model of time delay and time delay rate, effective restriction has been carried out to the search range of time delay and time delay rate, greatly improve the search efficiency of cross correlation process, so as to quickly obtain the time delay of each antenna and time delay rate value in the antenna array of strange land, support is provided for subsequent antenna array data processing.
Description
Technical field
The present invention relates to the signals based on prediction model in field of deep space exploration more particularly to a kind of strange land antenna array
The method for fast searching of time delay and time delay rate.
Background technique
With the movable continuous expansion of mankind's deep space exploration, the flying distance of spacecraft is more and more remoter, Spacecraft Launch
Signal also increases with distance more and more weaker.Since there are engineering poles for the bore and the technical indicator of receiver system of single side antenna
Limit needs to reach by antenna array technology lowest signal-to-noise required for receiving signal.The purpose of antenna array is briefly general
It includes are as follows: under identical transmission code rate, antenna array technology can face the reception distance of spacecraft with increasing；In identical reception
Under distance, antenna array technology can be improved the transmission bit rate between ground and spacecraft.
Strange land antenna array refer to using the existing large aperture antenna for being distributed in different zones and meanwhile observe spacecraft, then
The signal from each antenna is recorded by Digital Signal Processing, is synthesized, receives signal noise to reach to improve
The purpose of ratio.The advantage of this antenna array technology is to can use existing antenna and receiving device, it is only necessary to after increase
End data processing equipment can realize antenna array, and the lead time is short and at low cost.
With the project verification of mars exploration engineering, the deep space exploration activity in China has also started the expansion from the moon to Mars.
Since Mars is very remote apart from the earth, signal is decayed huge during space propagation, and relative to the moon, Mars distance increases
1000 times, signal space decaying increases about 60dB.The detector signal that ground receiver arrives is very faint, such as uses existing list
Antenna receives, and is unable to satisfy the science data downstream-on-demand of detector.If creating the bigger single antenna of bore to carry out data
It receives, due to being limited by all many conditions such as the single antenna engineering limit, development progress, research funds, so that entire project exists
Great developing risk.
Summary of the invention
(1) technical problems to be solved
In view of this, the main purpose of the present invention is to provide in a kind of strange land antenna array based on prediction model time delay and
Time delay rate method for fast searching, quickly to obtain the time delay of each antenna and time delay rate value in the antenna array of strange land.
(2) technical solution
The present invention provides a kind of time delay based on prediction model and time delay rate method for fast searching, includes the following steps: to walk
Rapid 1: according to aerial position and Observed Position, primary Calculation goes out observed object to the latency prediction value between antenna；Step
2: least square models fitting being carried out to the latency prediction value being calculated, obtains the latency prediction model of Time Continuous；Step
3: preliminary time delay and time delay rate being carried out to antenna array observation data using obtained latency prediction model and compensated, then using mutual
Correlation technique carries out cross correlation process to antenna data, scans for the residual error between time delay true value and latency prediction value.
In above scheme, the step 1 includes: step 101: read observed object tracking listed files (t, ra, dec) and
Each antenna geographical coordinate (x in the battle array of strange landi, yi, zi), wherein (t, ra, dec) is indicated in t moment, the right ascension of observed object and
Declination value；(xi, yi, zi) indicate terrestrial space rectangular coordinate system in each aerial position, subscript i be used to distinguish different days
Line has N number of antenna in battle array, then has N group (xi, yi, zi)；I takes 0,1...N-1；Step 102: according to classical celestial body time-delay calculation side
Method calculating observation target is to antenna and the geometric delays predicted value of reference point.
In above scheme, the time-delay calculation method of classics celestial body described in step 102 includes: step A1: input survey station coordinate
And detector position；Step A2: amendment survey station local coordinate system error as caused by tide, plate motion；Step A3: by ground heart
Spherical coordinate system is transformed into the earth's core celestial coordinate system；Step A4: the earth's core celestial coordinate system is transformed to by the sun by Lorentz transformation
It is mass center celestial coordinate system, calculates geometric delays in solar system mass center celestial coordinate system, and corrects solar system gravitating and make
At signal transmission path bending error；Step A5: solar system mass center celestial coordinate system is switched back to ground by Lorentz transformation
Heart celestial coordinate system obtains required geometric delays predicted value.
In above scheme, the step 2 includes: step 201: the geometry by obtained each antenna about the earth's core reference point
Latency prediction value τi(tj) read in, according to the kinetic characteristic of observed object, M segmentation is divided into above-mentioned prediction value list, M is nature
Number；Step 202: using least square method, fitting of a polynomial is carried out to above-mentioned one section of predicted value, obtains multinomial model y；Step
203: assessment multinomial model y fitting precision, fitting precision are met the requirements, and obtain latency prediction model.
In above scheme, least square method described in step 202 carries out least square fitting using 5 rank multinomials.
In above scheme, the step 203 includes: according to formulaAn algnment accuracy is calculated, f is
Observation signal frequency, unit Hz；Error of fitting is to pass through formulaIt acquires, y in formulajIt represents
Multinomial model y is in tjThe value at moment, τ0(tj), τ1(tj) correspond to Miyun station and Station in Kunming t in geometric delays calculation result tablejWhen
The geometric delays calculated value at quarter, n indicate the number of each piecewise prediction value；Error of fitting RMS needs to be less than algnment accuracy；If
Precision is met the requirements, then multinomial coefficient can be used as the latency prediction model of the antenna, if fitting precision is unsatisfactory for requiring,
Return step 201, adjustment segmentation or increase polynomial order, re-start fitting, until fitting precision is met the requirements.
In above scheme, residual error between time delay true value described in step 3 and latency prediction value includes remaining time delay and residual
Remaining time delay rate.
In above scheme, the step 3 includes: step 301: choosing the maximum antenna of antenna array medium caliber and is used as with reference to day
Line, 1 latency prediction model value that antenna array is obtained in selecting step 203 subtract the prediction model value of reference antenna, obtain it
He is delay inequality value prediction model y (i, t of the antenna relative to reference antennaj)；Step 302: reading in reference antenna and observe data OR
(tj) and battle array in other antenna observe data Oi(tj), the DC component of removal observation data obtains Oa R(tj), Oa i(tj)；
Step 303: from Oa R(tj) 2 are taken in datanA data, delay inequality value prediction model y (i, the t obtained using step 301j) to sight
Measured data Oa i(tj) delay compensation and the compensation of time delay rate are carried out, obtain compensated 2nA data Oa i(tj- y (i, tj))；Step
304: respectively to OaR(tj), [Oa i(tj- y (i, tj))] ' Fast Fourier Transform is carried out, and cross-correlation is carried out, obtain cross-correlation
Frequency spectrum fft (OR a(tj))×fft*(Oa i(tj- y (i, tj)))；Seek cross-correlation frequency spectrum fft (OR a(tj))×fft*(Oa i(tj- y (i,
tj))) phase value, then to phase value solution wind, then using least square method to phase curve progress once linear letter
Number fitting, obtain this 2nThe remaining time delay Δ τ of a data1；Step 305: removing 2nA data equally carry out above-mentioned 304 step
It calculates, obtains down 2nThe remaining time delay Δ τ of a data2, time delay rate is calculated
Step 306: the remaining time delay Δ τ that above-mentioned search is obtained1With time delay rateBe added to corresponding delay inequality value prediction model y (i,
tj) in, the true Time Delay Model used for subsequent antenna group battle array data processing can be obtained.
(3) beneficial effect
Time delay and time delay rate method for fast searching provided by the invention, it is possessed to have the active effect that
The prediction model for introducing time delay and time delay rate, to the effective restriction in the search range of time delay and time delay rate, greatly
Ground improves the search efficiency of cross correlation process, so as to quickly obtain the time delay and time delay of each antenna in the antenna array of strange land
Rate value provides support for subsequent antenna array data processing.
Detailed description of the invention
Fig. 1 is that strange land antenna array signal receives schematic diagram；
Fig. 2 is the time delay and time delay rate method for fast searching flow chart in strange land antenna array of the present invention based on prediction model；
Fig. 3 is classical celestial body time-delay calculation flow chart；
Fig. 4 is that a kind of model calculation value of specific embodiment of the invention and fitting of a polynomial value compare；
Fig. 5 be a kind of specific embodiment of the invention there are the cross-correlation coefficients of time delay；
Fig. 6 be a kind of specific embodiment of the invention there are the cross-correlation interference fringes of remnants time delay rate；
Fig. 7 is the cross-correlation coefficient after a kind of remaining delay compensation of specific embodiment of the invention；
Fig. 8 is a kind of postrotational interference fringe of striped of specific embodiment of the invention；
Fig. 9 is cross-correlation phase spectrum before a kind of fractional delay of specific embodiment of the invention adjusts；
Figure 10 is a kind of fractional delay cross-correlation phase spectrum adjusted of specific embodiment of the invention.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with specific embodiment, and reference
Attached drawing, the present invention is described in further detail.
In order to meet mars exploration mission requirements, proposed adoption strange land group battle array received mode expires in mars exploration task
The demand of sufficient data receiver.Compared with locally organizing battle array, since the path of pick-up probe downlink signal is different, the day of different location
The signal that line receives can generate biggish time delay and time delay rate, and the amendment of time delay and time delay rate is to signal combined coefficient, synthesis
The amplitude of signal has a major impact.In consideration of it, the present invention provides in a kind of strange land antenna array based on prediction model time delay and
Time delay rate method for fast searching.
In embodiments of the present invention, strange land antenna array is made of N number of antenna, finally can simplify for multiple 2 antenna arrays into
Row data processing is used to explain the present invention using 2 antenna arrays as illustrative example herein, but not as to limit of the invention
Fixed, one of antenna is located at Beijing, another antenna is located at Kunming, as shown in Figure 1, Fig. 1 is that strange land antenna array signal connects
Receive schematic diagram.
τ represents the geometric delays (time difference) between spacecraft two antennas of arrival in Fig. 1,It represents spacecraft and reaches two
Geometric delays rate (time difference rate of change) between a antenna, g represent the geometry distance between spacecraft two antennas of arrival
Difference, c represent the light velocity.As can be seen from Figure 1 signal is during spatial, due to the earth and Spacecraft Relative Motion,
The many factors such as atmospheric refraction, ionospheric disturbance and reception channel, the time delay value and time delay rate for reaching Liang Ge earth station are
It is continually changing.In order to which the data in the antenna array of strange land are carried out signal synthesis, it is necessary to time delay value and time delay rate into
Row compensation.Time delay mainly caused by geometric delays, clock when extend to atmospheric time delay three parts and constitute.Geometric delays are
Accounting maximum a part in Yanzhong when entire, is mainly caused as observation station and geometric position locating for observed object.It is seen knowing
In the case where geometric position locating for survey station and observed object, the predicted value of geometric delays can be obtained by calculation.Due to having
The residual error search efficiency of the restriction of predicted value, subsequent time delay and time delay rate will greatly improve.
Fig. 2 is the time delay and time delay rate method for fast searching flow chart in strange land antenna array of the present invention based on prediction model,
Method includes the following steps: predictor calculation, prediction model fitting and residual error search, in which:
Step 1: predictor calculation is according to aerial position and Observed Position, and primary Calculation goes out observed object to antenna
Between geometric delays predicted value, which specifically includes:
Step 101: reading each antenna geographical coordinate in observed object tracking listed files (t, ra, dec) and strange land battle array
(xi, yi, zi)；Wherein (t, ra, dec) is indicated in t moment, the right ascension and declination value of observed object；(xi, yi, zi) indicate the earth
Each aerial position in rectangular coordinate system in space, subscript i are used to distinguish different antennas, have N number of antenna in battle array, then have N group
(xi, yi, zi), i takes 0,1...N-1.
Observed object tracking file be one group by Observed Position data group at list.If observed object is to defend
Star, then observed object tracking file is exactly one group of satellite position data being calculated by orbit elements of satellite.For convenience
Understand that observed object tracks file data format, provides observed object tracking text by taking No. three Satellite Tracking files of the goddess in the moon as an example below
Part data format:
| Year | MM | DD | HH | MM | SS | Distance | RA | DEC |
| 2015 | 5 | 10 | 0 | 0 | 0 | 374602 | 20.0849 | -15.1805 |
| 2015 | 5 | 10 | 0 | 1 | 0 | 374600 | 20.0856 | -15.1788 |
| 2015 | 5 | 10 | 0 | 2 | 0 | 374597 | 20.0862 | -15.1771 |
| 2015 | 5 | 10 | 0 | 3 | 0 | 374595 | 20.0869 | -15.1755 |
| 2015 | 5 | 10 | 0 | 4 | 0 | 374593 | 20.0875 | -15.1738 |
| 2015 | 5 | 10 | 0 | 5 | 0 | 374591 | 20.0882 | -15.1721 |
| 2015 | 5 | 10 | 0 | 6 | 0 | 374589 | 20.0888 | -15.1704 |
| 2015 | 5 | 10 | 0 | 7 | 0 | 374587 | 20.0895 | -15.1688 |
| 2015 | 5 | 10 | 0 | 8 | 0 | 374585 | 20.0901 | -15.1671 |
| 2015 | 5 | 10 | 0 | 9 | 0 | 374583 | 20.0908 | -15.1654 |
Parameters are meant that in table: Year MM DD HH MM SS indicate time identifier, format be year month
Day when divide second；Distance indicates spacecraft to the distance in earth the earth's core；RA (Right ascension) indicates observation mesh
Target right ascension value；DEC (Declination) indicates the declination value of the observed object.
The geographical coordinate for reading each antenna in the antenna array of strange land, at this point, N=2, has 2 antennas, be located at, Kunming
And Beijing, it is as shown in the table:
| Name | X(m) | Y(m) | Z(m) |
| Km | -1281152.939 | 5640864.407 | 2682653.403 |
| Bj | -2201304.82 | 4324789.045 | 4125367.718 |
Each antenna code name in the antenna array of the strange land Name in table, Km indicate that 40 meters of antennas of Station in Kunming, Bj indicate Miyun Region of Beijing
It stands 50 meters of antennas；X (m) Y (m) Z (m) respectively indicate X-axis of each antenna in geocentric rectangular coordinate system, Y-axis, Z axis numerical value,
Unit is rice.
Step 102: when according to classical celestial body time-delay calculation method calculating observation target to antenna and the geometry of reference point
Prolong predicted value.
In the scope that international celestial reference frame (ICRF) defines, using the earth's core as reference point, calculates and see
Target is surveyed to antenna and the latency prediction value list τ of reference pointi(tj), wherein tjIndicate the time, subscript i is used to
Different antennas is distinguished, there is N number of antenna in battle array, then has N column geometric delays predicted value τi(tj), i takes 0,1...N-1.
In Celestial Reference System, Celestial Reference System is approximately inertial coodinate system.In the coordinate system, the origin of default is
Solar system mass center, the plane that the equatorial plane is defined as the equator (J2000) of epoch 2000 and the first point of Aries determines.In terrestrial coordinate system,
Using conventional international origin (CIO) (CIO, Conventional International Origin) major axes orientation determined and accordingly
The equatorial plane.Using the baseline vector between the orbital data and antenna of detector, calculating process such as Fig. 3 institute of geometric delays is carried out
Show.Fig. 3 is classical celestial body time-delay calculation flow chart, first input survey station coordinate and detector position, is then corrected by tide, plate
Block movement etc. caused by survey station local coordinate system error, by the earth's core terrestrial coordinate system be transformed into the earth's core celestial coordinate system (amendment the precession of the equinoxes,
Error caused by nutating, perturbation), the earth's core celestial coordinate system is then transformed to by solar system mass center celestial sphere by Lorentz transformation and is sat
Mark system, calculates geometric delays in solar system mass center celestial coordinate system, and corrects the transmission of signal caused by solar system gravitating
Solar system mass center celestial coordinate system is switched back to the earth's core celestial coordinate system finally by Lorentz transformation, obtained by path bending error
To required geometric delays.
According to above-mentioned calculating, using the earth's core as reference point, the geometric delays of calculating observation target to antenna and reference point are pre-
Measured value list τi(tj), wherein tjIndicate the time, subscript i is used to distinguish different antennas, there are 2 antennas in battle array, then there are 2 column several
When predicted value τ is prolongedi(tj), i takes 0,1...N-1.
In order to facilitate the calculating process for understanding latency prediction value, one group is shown below with No. three landers of the goddess in the moon as observation
Target (2 divide -59 seconds 0 second when the period is 10 days 00 May in 2015), 40 meters of antennas of Station in Kunming and the antenna conduct of 50 meters of Miyun station
Strange land group array antenna, geometric delays predictor calculation result (the geometric delays value that the earth's core is reference point).Geometric delays are predicted
Value calculated result was segmented according to 60 seconds, this is wherein one section.
Geometric delays calculation result table
Step 2: prediction model fitting is to be carried out using least square method to the above-mentioned latency prediction value being calculated
Least square models fitting obtains the geometric delays prediction model of Time Continuous；The step specifically includes:
Step 201: each antenna is calculated in above-mentioned steps 1 and predicts value list about the geometric delays of the earth's core reference point
τi(tj) read in, according to the kinetic characteristic of observed object, M segmentation is divided into above-mentioned prediction value list, M is natural number.It corresponds to
It states in calculated examples, Miyun station in table and Station in Kunming latency prediction value is read in, and was segmented with 60 second time.
Step 202: using least square method, fitting of a polynomial is carried out to above-mentioned one section of predicted value, obtains multinomial model
y。
It corresponds in above-mentioned calculated examples, is assessed in conjunction with detector motion characteristic and by multiple fitting precision, using 5
Rank multinomial carries out least square fitting, can satisfy subsequent calculating requirement.Obtained multinomial model are as follows:
Y=6212.21513+0.110956058X+ (- 1.236351374e-05X2)+(-3.101422866e-10X3)+
(3.286324942e-12X4)+(-1.306814583e-14X5)。
Step 203: assessment multinomial model y fitting precision, fitting precision are met the requirements, and obtain latency prediction model.
Error of fitting RMS is needed to be less thanF is observation signal frequency, unit Hz.If precision meets
It is required that then multinomial coefficient can be used as the prediction model of the antenna, and if fitting precision is unsatisfactory for requiring, return step 201,
Adjustment segmentation increases polynomial order, re-starts fitting, until fitting precision is met the requirements, the M group multinomial coefficient
It can be used as the prediction model of the antenna.Then above-mentioned models fitting work successively is carried out to all antennas, obtained entire different
The prediction model of ground antenna array.
It corresponds in above-mentioned calculated examples, multinomial model y=6212.21513+0.110956058X+ (-
1.236351374e-05X2)+(-3.101422866e-10X3)+(3.286324942e-12X4)+(-1.306814583e-
14X5) error of fitting RMS=2.862e-07us, it is root-mean-square error.The error of fitting is to pass through formulaIt acquires, y in formulajMultinomial model y is represented in tjThe value at moment, τ0(tj), τ1(tj) corresponding several
When in calculation result table Miyun station and Station in Kunming t are prolongedjThe geometric delays calculated value at moment.
The model calculation value and fitting of a polynomial value for being illustrated in figure 4 a kind of specific embodiment of the invention compare, horizontal axis
For the time, the longitudinal axis is time delay, has been described in conjunction with the embodiments fitting of a polynomial value and model calculation value error very little, can be used quasi-
Conjunction obtains multinomial model as Time Delay Model.
Step 3: residual error search is to carry out preliminary time delay and time delay to antenna array observation data using above-mentioned prediction model
Then rate compensation carries out cross correlation process to antenna data using cross-correlation method, to residual between time delay true value and predicted value
Difference scans for；The step specifically includes:
Step 301: choosing the maximum antenna of antenna array medium caliber as reference antenna, obtain antenna in selecting step 203
1 latency prediction model value of battle array subtracts the prediction model value of reference antenna, obtain other antennas relative to reference antenna when
Prolong difference prediction model y (i, tj)。
It corresponds in above-mentioned calculated examples, chooses 50 meters of Miyun station aperture antenna as reference antenna,
Step 302: reading in reference antenna and observe data OR(tj) and battle array in other antenna observe data Oi(tj), it goes
Except the DC component of observation data, Oa R(tj), Oa i(tj) obtain.
It corresponds in above-mentioned calculated examples, for reference antenna, reads the record data of one section of Miyun station antenna respectively
OR(tj), seek the average value (DC component) of this segment dataThen by this segment record data OR
(tj) subtractObtain Oa R(tj), the processing of other antennas and so on.
Step 303: from Oa R(tj) 2 are taken in datanA data, the delay inequality value prediction model y obtained using step 301
(i, tj) to observation data Oa i(tj) delay compensation and the compensation of time delay rate are carried out, obtain compensated 2nA data Oa i(tj- y (i,
tj))。
It corresponds in above-mentioned calculated examples, it is assumed that first from Oa R(tj) in take 256 (n takes 8 in this example) a data, then take pre-
Model tj=0 is surveyed, the latency prediction value τ=6.21221513e-03s at the moment, time delay rate predicted value are obtainedSince the sampling rate of antenna record data is 1e+07, the sampling time of this each data
Ts=1e-07s, that delay compensation data bits=τ/1e-7=62122 carry out delay compensation to another antenna data,
Just the identical record moment is needed to skip delay compensation data bits backward, reads 256 data of data, this data ability and ginseng
Examine 256 data integer-bits alignment of antenna, less than one sampling Ts of alignment error.
Then, then to this segment data carry out Doppler shift compensation.
Step 304: respectively to Oa R(tj), Oa i(tj- y (i, tj)) Fast Fourier Transform is carried out, and cross-correlation is carried out, it obtains
To cross-correlation frequency spectrum fft (OR a(tj))×fft*(Oa i(tj- y (i, tj)))；Seek cross-correlation frequency spectrum fft (OR a(tj))×fft*(Oa i
(tj- y (i, tj))) phase value, then to phase value solution wind, then using least square method to phase curve progress one
Sublinear functions fitting, obtain this 2nThe remaining time delay Δ τ of a data1。
Step 305: removing 2nA data equally carry out above-mentioned 304 step and calculate, obtain down 2nThe remaining time delay of a data
Δτ2, time delay rate is calculated
Step 306: the remaining time delay Δ τ that above-mentioned search is obtained1With time delay rateIt is added to corresponding geometric delays prediction
Y (i, tj) in, the true Time Delay Model used for subsequent antenna group battle array data processing can be obtained.
Correspond to Δ τ in the present embodiment1=5e-7s,So true Time Delay Model
All observation data of the antenna can be obtained in operation to remaining M-1 group Data duplication step 201 to step 306
Corresponding true Time Delay Model.
Above-mentioned steps 101 are carried out to all operations of step 306 to other antennas remaining in antenna array, so that it may obtain institute
There is the corresponding true Time Delay Model of antenna observation data.
It corresponds in above-mentioned calculated examples, preliminary time delay is carried out to two station data and time delay rate corrects, it is right after the completion of correction
Two station data carry out cross correlation process, and it is as shown in Figure 5 and Figure 6 to obtain cross-correlation coefficient, related streak.
Be illustrated in figure 5 a kind of specific embodiment of the invention there are the cross-correlation coefficient figure of time delay, horizontal axis is the time,
The longitudinal axis is cross-correlation coefficient amplitude, has been described in conjunction with the embodiments since remaining time delay exists, the maximum value of cross-correlation coefficient does not have
Time of occurrence zero point, there are certain deviations.
Be illustrated in figure 6 a kind of specific embodiment of the invention there are the cross-correlation interference fringe picture of remnants time delay rate,
Horizontal axis is the time, and the longitudinal axis is cross-correlation interference fringe phase, has been described in conjunction with the embodiments since remaining time delay rate exists, cross-correlation
Interference fringe phase slope is not zero.
From cross correlation results as can be seen that since there is a certain error for the estimated value of model, related coefficient and related frequency
There are certain deviation, this deviation is exactly between model time delay value and true time delay for the phase of spectrum and ideal autocorrelation spectrum
Residual error.Estimate to obtain remaining time delay to be 5e-7s, time delay rate 4.11e-11s/s by further time delay and time delay rate.
Cross-correlation coefficient figure after being illustrated in figure 7 a kind of remaining delay compensation of specific embodiment of the invention, horizontal axis
For the time, the longitudinal axis is cross-correlation coefficient amplitude, has been described in conjunction with the embodiments due to being compensated remaining time delay, cross correlation
Several maximum values appear in time zero.
It is illustrated in figure 8 the cross-correlation interference fringe picture of remaining time delay rate compensation, horizontal axis is the time, and the longitudinal axis is dry for cross-correlation
Fringe phase is related to, has been described in conjunction with the embodiments due to being compensated remaining time delay rate, cross-correlation interference fringe phase slope
It is substantially zeroed.
It is illustrated in figure 9 cross-correlation phase frequency spectrum figure before fractional delay adjusts, horizontal axis is frequency, and the longitudinal axis is phase, in conjunction with
Embodiment illustrates the presence due to fractional bits time delay, and phase slope is not zero in cross-correlation phase frequency spectrum figure.
It is as shown in Figure 10 fractional delay cross-correlation phase frequency spectrum figure adjusted, horizontal axis is frequency, and the longitudinal axis is phase, knot
It closes embodiment and illustrates that, due to compensating to fractional bits time delay, phase slope is substantially zeroed in cross-correlation phase frequency spectrum figure.
From cross correlation results as can be seen that cross-correlation coefficient, striped and phase spectrum are consistent with ideal autocorrelation spectrum.
Time delay and time delay rate method for fast searching of the invention introduces the prediction model of time delay and time delay rate, to time delay and
The search range of time delay rate has carried out effective restriction, the search efficiency of cross correlation process is greatly improved, so as to quick
The time delay of each antenna and time delay rate value in the antenna array of strange land are obtained, provides support for subsequent antenna array data processing.
Particular embodiments described above has carried out further in detail the purpose of the present invention, technical scheme and beneficial effects
Describe in detail bright, it should be understood that the above is only a specific embodiment of the present invention, is not intended to restrict the invention, it is all
Within the spirit and principles in the present invention, any modification, equivalent substitution, improvement and etc. done should be included in protection of the invention
Within the scope of.
Claims (7)
1. a kind of time delay and time delay rate method for fast searching based on prediction model, which comprises the steps of:
Step 1: according to aerial position and Observed Position, primary Calculation goes out observed object to the latency prediction between antenna
Value；
Step 2: least square models fitting being carried out to the latency prediction value being calculated, obtains the latency prediction mould of Time Continuous
Type；
Step 3: preliminary time delay and time delay rate being carried out to antenna array observation data using obtained latency prediction model and compensated, so
Cross correlation process is carried out to antenna data using cross-correlation method afterwards, the residual error between time delay true value and latency prediction value is carried out
Search；
Wherein, the step 2 includes:
Step 201: the geometric delays predicted value τ by obtained each antenna about the earth's core reference pointi(tj) read in, according to observation
The kinetic characteristic of target is divided into M segmentation to above-mentioned prediction value list, and M is natural number；
Step 202: using least square method, fitting of a polynomial is carried out to one section of predicted value, obtains multinomial model y；
Step 203: assessment multinomial model y fitting precision, fitting precision are met the requirements, and obtain latency prediction model.
2. the time delay and time delay rate method for fast searching according to claim 1 based on prediction model, which is characterized in that institute
Stating step 1 includes:
Step 101: reading each antenna geographical coordinate (x in observed object tracking listed files (t, ra, dec) and strange land battle arrayi,
yi, zi), wherein (t, ra, dec) is indicated in t moment, the right ascension and declination value of observed object；(xi, yi, zi) indicate terrestrial space
Each aerial position in rectangular coordinate system, subscript i are used to distinguish different antennas, have N number of antenna in battle array, then have N group (xi,
yi, zi), i takes 0,1...N-1；
Step 102: the geometric delays according to classical celestial body time-delay calculation method calculating observation target to antenna and reference point are pre-
Measured value.
3. the time delay and time delay rate method for fast searching according to claim 2 based on prediction model, which is characterized in that step
Classics celestial body time-delay calculation method described in rapid 102 includes:
Step A1: input survey station coordinate and detector position；
Step A2: amendment survey station local coordinate system error as caused by tide, plate motion；
Step A3: the earth's core terrestrial coordinate system is transformed into the earth's core celestial coordinate system；
Step A4: the earth's core celestial coordinate system is transformed to by solar system mass center celestial coordinate system by Lorentz transformation, in the solar system
Geometric delays are calculated in mass center celestial coordinate system, and correct signal transmission path bending error caused by solar system gravitating；
Step A5: switching back to the earth's core celestial coordinate system for solar system mass center celestial coordinate system by Lorentz transformation, obtains required
Geometric delays predicted value.
4. the time delay and time delay rate method for fast searching according to claim 1 based on prediction model, which is characterized in that step
Least square method described in rapid 202 carries out least square fitting using 5 rank multinomials.
5. the time delay and time delay rate method for fast searching according to claim 1 based on prediction model, which is characterized in that institute
Stating step 203 includes:
According to formulaAn algnment accuracy is calculated, f is observation signal frequency, unit Hz；Error of fitting is to pass through public affairs
FormulaIt acquires, y in formulajMultinomial model y is represented in tjThe value at moment, τ0(tj), τ1(tj) corresponding
Miyun station and Station in Kunming t in geometric delays calculation result tablejThe geometric delays calculated value at moment, n indicate each piecewise prediction value
Number；Error of fitting RMS needs to be less than algnment accuracy；If precision is met the requirements, multinomial coefficient can be used as the day
The latency prediction model of line, if fitting precision is unsatisfactory for requiring, return step 201, adjustment is segmented or increases order of a polynomial
Number, re-starts fitting, until fitting precision is met the requirements.
6. the time delay and time delay rate method for fast searching according to claim 1 based on prediction model, which is characterized in that step
Residual error between time delay true value and latency prediction value described in rapid 3 includes remaining time delay and remaining time delay rate.
7. the time delay and time delay rate method for fast searching according to claim 1 based on prediction model, which is characterized in that institute
Stating step 3 includes:
Step 301: choosing the maximum antenna of antenna array medium caliber as reference antenna, obtain the 1 of antenna array in selecting step 203
A latency prediction model value subtracts the prediction model value of reference antenna, obtains time delay difference of other antennas relative to reference antenna
Prediction model y (i, tj)；
Step 302: reading in reference antenna and observe data OR(tj) and battle array in other antenna observe data Oi(tj), removal observation
The DC component of data, obtains Oa R(tj), Oa i(tj)；
Step 303: from Oa R(tj) 2 are taken in datanA data, delay inequality value prediction model y (i, the t obtained using step 301j)
To observation data Oa i(tj) delay compensation and the compensation of time delay rate are carried out, obtain compensated 2nA data 0a i(tj- y (i, tj))；
Step 304: respectively to Oa R(tj), 0a i(tj- y (i, tj)) Fast Fourier Transform is carried out, and cross-correlation is carried out, it obtains mutually
Relevant frequency spectrum fft (OR a(tj))×fft*(0a i(tj- y (i, tj)))；Seek cross-correlation frequency spectrum fft (0R a(tj))×fft*(0a i(tj-
Y (i, tj))) phase value, then to phase value solution wind, then using least square method to phase curve progress primary line
Property Function Fitting, obtain this 2nThe remaining time delay Δ τ of a data1；
Step 305: removing 2nA data equally carry out above-mentioned 304 step and calculate, obtain down 2nThe remaining time delay Δ τ of a data2,
Time delay rate is calculated
Step 306: the remaining time delay Δ τ that above-mentioned search is obtained1With time delay rateIt is added to corresponding delay inequality value prediction model
Y (i, tj) in, the true Time Delay Model used for subsequent antenna group battle array data processing can be obtained.
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